Yes, you still want to use an AI. I would not count on a DHT based steroid like Mast or Proviron to completely control estrogen. In fact, I have never seen it really lower estrogen. If it does, the effect will be mild. It is a great compound though. With Mast P, 100mg EOD or 400 to 500mg of long acting Mast E would be good, plus with the long actin stuff you only need 2 shots a day.